Microbes: Cleaning the Environment Naturally

In the natural world, humans are far from being the foremost chemists. At least that’s what Catherine Drennan, a professor of biology and chemistry and the Massachusetts Institute of Technology (MIT), believes.

“Microbes are the greatest chemists, that’s why I like them,” Drennan says in an interview with R&D Magazine. “Humans are really kind of boring in the chemistry that they do, to be honest…We utilize the microbes to do the cool stuff.”

Currently, Drennan is part of a team attempting to understand how microbes metabolize hydrocarbons—which are prevalent molecular components of crude oil—for growth and survival.

“We discovered these microbes are living off these things that we want to get rid of,” says Drennan.



Ideally, the discovery may lead to microbes helping humans clean up after oil spills in aquatic environments. “I love the idea of cleaning up the environment naturally,” says Drennan.

The researchers explored how the denitrifying bacterium Thauera aromatica metabolized the hydrocarbon toluene. First, the microbe needs to generate a more reactive molecule in order to make the toluene useful.

The pairing of the enzyme benzylsuccinate synthase (BSS), which naturally occurs within the microbe, and the substrate molecule fumarate, also present in the microbe, allows the breakdown of toluene. “The (BSS) acts as a catalyst, encouraging a reaction between the toluene and the fumarate to generate benzylsuccinate,” according to MIT. “The conversion of toluene to benzylsuccinate makes it more reactive…and the first step in the metabolism process is then possible.”

Drennan describes BSS as part of the ancient glycyl radical enzyme family.

According to Michael Funk, a graduate student at MIT, revealing how non-binding hydrocarbons like toluene are broken down is a starting point for potential bioremediation efforts. “This enzyme (BSS) utilizes toluene, and everything is packed very tightly around that molecule. So it’s not like it can just take anything—it’s very specific for that particular molecule,” Funk said.  

They’ve “really been modified to do this toluene chemistry,” Drennan says.

Though Drennan and her team focused on revealing the structural information behind the chemical reaction, she hopes others will apply the information to future field work.

In the microbe-aided human future, Drennan sees cultured microbes being introduced to water environments near oil refineries, where they can thrive and multiply due to ample amounts of food.

Already, microbes thrive in oil refinery environments. Attracted to the toluene, some microbes grow unchecked on machinery, clogging up and eroding pipes, which potentially leads to spills. “Microbes can be really fantastic for cleaning up certain kinds of environments” but “you wouldn’t want them in a place where they can cause damage,” she says.

What needs to be designed is a potential enzyme inhibitor capable of being coated on the machinery to deter microbial growth in harmful areas, according to Drennan.